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Duanmu Z, Ali SJV, Allen J, Cheng LK, Stommel M, Xu W. A Review of In Vitro and In Silico Swallowing Simulators: Design and Applications. IEEE Trans Biomed Eng 2024; 71:2042-2057. [PMID: 38294923 DOI: 10.1109/tbme.2024.3360893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
Swallowing is a primary and complex behaviour that transports food and drink from the oral cavity, through the pharynx and oesophagus, into the stomach at an appropriate rate and speed. To understand this sophisticated behaviour, a tremendous amount of research has been carried out by utilising the in vivo approach, which is often challenging to perform, poses a risk to the subjects if interventions are undertaken and are seldom able to control for confounding factors. In contrast, in silico (computational) and in vitro (instrumental) methods offer an alternate insight into the process of the human swallowing system. However, the appropriateness of the design and application of these methods have not been formally evaluated. The purpose of this review is to investigate and evaluate the state of the art of in vitro and in silico swallowing simulators, focusing on the evaluation of their mechanical or computational designs in comparison to the corresponding swallowing mechanisms during various phases of swallowing (oral phase, pharyngeal phase and esophageal phase). Additionally, the potential of the simulators is also discussed in various areas of applications, including the study of swallowing impairments, swallowing medications, food process design and dysphagia management. We also address current limitations and recommendations for the future development of existing simulators.
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Seifelnasr A, Ding P, Si X, Biondi A, Xi J. Oropharyngeal swallowing hydrodynamics of thin and mildly thick liquids in an anatomically accurate throat-epiglottis model. Sci Rep 2024; 14:11945. [PMID: 38789468 PMCID: PMC11126673 DOI: 10.1038/s41598-024-60422-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 04/23/2024] [Indexed: 05/26/2024] Open
Abstract
Understanding the mechanisms underlying dysphagia is crucial in devising effective, etiology-centered interventions. However, current clinical assessment and treatment of dysphagia are still more symptom-focused due to our limited understanding of the sophisticated symptom-etiology associations causing swallowing disorders. This study aimed to elucidate the mechanisms giving rise to penetration flows into the laryngeal vestibule that results in aspirations with varying symptoms. Methods: Anatomically accurate, transparent throat models were prepared with a 45° down flapped epiglottis to simulate the instant of laryngeal closure during swallowing. Fluid bolus dynamics were visualized with fluorescent dye from lateral, rear, front, and endoscopic directions to capture key hydrodynamic features leading to aspiration. Three influencing factors, fluid consistency, liquid dispensing site, and dispensing speed, were systemically evaluated on their roles in liquid aspirations. Results: Three aspiration mechanisms were identified, with liquid bolus entering the airway through (a) the interarytenoid notch (notch overflow), (b) cuneiform tubercle recesses (recess overflow), and (c) off-edge flow underneath the epiglottis (off-edge capillary flow). Of the three factors considered, liquid viscosity has the most significant impact on aspiration rate, followed by the liquid dispensing site and the dispensing speed. Water had one order of magnitude higher aspiration risks than 1% w/v methyl cellulose solution, a mildly thick liquid. Anterior dispensing had higher chances for aspiration than posterior oropharyngeal dispensing for both liquids and dispensing speeds considered. The effects of dispending speed varied. A lower speed increased aspiration for anterior-dispensed liquids due to increased off-edge capillary flows, while it significantly reduced aspiration for posterior-dispensed liquids due to reduced notch overflows. Visualizing swallowing hydrodynamics from multiple orientations facilitates detailed site-specific inspections of aspiration mechanisms.
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Affiliation(s)
- Amr Seifelnasr
- Department of Biomedical Engineering, University of Massachusetts, 1 University Ave., Falmouth Hall 302I, Lowell, MA, 01854, USA
| | - Peng Ding
- Department of Otolaryngology-Head and Neck Surgery, Cleveland Clinic Lerner College of Medicine, 9501 Euclid Ave, Cleveland, OH, 44195, USA
| | - Xiuhua Si
- Department of Mechanical Engineering, California Baptist University, 8432 Magnolia Ave, Riverside, CA, 92504, USA
| | - Andres Biondi
- Department of Electrical and Computer Engineering, University of Massachusetts, 1 University Ave., Lowell, MA, 01854, USA
| | - Jinxiang Xi
- Department of Biomedical Engineering, University of Massachusetts, 1 University Ave., Falmouth Hall 302I, Lowell, MA, 01854, USA.
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Hino H, Suzuki T, Maekawa K, Ita R, Sasa A, Kulvanich S, Takei E, Magara J, Tsujimura T, Inoue M. Effect of bolus property on swallowing dynamics in patients with dysphagia. J Oral Rehabil 2024. [PMID: 38685709 DOI: 10.1111/joor.13709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/20/2024] [Accepted: 04/12/2024] [Indexed: 05/02/2024]
Abstract
BACKGROUND Modification of foods or liquids is commonly administered as part of dysphagia treatment. However, no consensus exists on the parameters for defining texture-modified food for patients with dysphagia. OBJECTIVES The aim of this study was to evaluate the effect of food/liquid material on swallowing physiology in patients with dysphagia and to discuss the optimal food choice for direct swallowing therapy. MATERIALS AND METHODS A total of 140 patients underwent a videofluoroscopic swallowing study using three test foods/liquids: 3 mL of mildly thick liquid (Thick liquid), jelly made of agar and polysaccharide (Jelly) and jelly made of pectin (Reset gel). Outcome measures of videofluoroscopic images, bolus transit time and hyoid movements were compared. RESULTS The frequency of chewing movements was highest for Jelly, followed by Reset gel and Thick liquid. While the probability of oral residue was the highest for Reset gel, pharyngeal residue after swallowing was high for Thick liquid as compared to Jelly and Reset gel. Oral transit time and pharyngeal transit time for Thick liquid were significantly smaller than that for Jelly and Reset gel. Pharyngeal delay time was significantly smaller for Thick liquid than that for Jelly and Reset gel. There was no difference in hyoid elevation time and hyoid movement time among the conditions. CONCLUSION Mildly thick liquid material may be optimal for patients with primarily oral motor function impairment and jelly, such as Reset gel, may be more suitable for patients with primarily pharyngeal motor function impairment or oral and pharyngeal coordinative motor function decline.
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Affiliation(s)
- Haruka Hino
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Taku Suzuki
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kazuya Maekawa
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Reiko Ita
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Anna Sasa
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Sirima Kulvanich
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
- Department of Community Dentistry & Gerodontology, Faculty of Dentistry, Thammasat University, Pathumthani, Thailand
| | - Eri Takei
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Jin Magara
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Takanori Tsujimura
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Makoto Inoue
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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Wang K, Cheng Z, Qiao D, Xie F, Zhao S, Zhang B. Polysaccharide-dextrin thickened fluids for individuals with dysphagia: recent advances in flow behaviors and swallowing assessment methods. Crit Rev Food Sci Nutr 2024:1-25. [PMID: 38556920 DOI: 10.1080/10408398.2024.2330711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide-dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide-dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future.
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Affiliation(s)
- Kedu Wang
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
- Chongqing Key Laboratory of Speciality Food Co-Built by Sichuan and Chongqing, College of Food Science, Southwest University, Chongqing, China
| | - Zihang Cheng
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
- Chongqing Key Laboratory of Speciality Food Co-Built by Sichuan and Chongqing, College of Food Science, Southwest University, Chongqing, China
| | - Dongling Qiao
- Chongqing Key Laboratory of Speciality Food Co-Built by Sichuan and Chongqing, College of Food Science, Southwest University, Chongqing, China
| | - Fengwei Xie
- Department of Chemical Engineering, University of Bath, Bath, UK
- School of Engineering, Newcastle University, Newcastle upon Tyne, UK
| | - Siming Zhao
- College of Food Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Binjia Zhang
- Chongqing Key Laboratory of Speciality Food Co-Built by Sichuan and Chongqing, College of Food Science, Southwest University, Chongqing, China
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Leichter DM, Stark NE, Leary OP, Brodsky MB, Gilbert RJ, Nicosia MA. Two dimensional computational model coupling myoarchitecture-based lingual tissue mechanics with liquid bolus flow during oropharyngeal swallowing. Comput Biol Med 2022; 145:105446. [PMID: 35390748 DOI: 10.1016/j.compbiomed.2022.105446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/13/2022] [Accepted: 03/21/2022] [Indexed: 11/25/2022]
Abstract
Biomechanical relationships involving lingual myoanatomy, contractility, and bolus movement are fundamental properties of human swallowing. To portray the relationship between lingual deformation and bolus flow during swallowing, a weakly one-way solid-fluid finite element model (FEM) was derived employing an elemental mesh aligned to magnetic resonance diffusional tractography (Q-space MRI, QSI) of the human tongue, an arbitrary Lagrangian-Eulerian (ALE) formulation with remeshing to account for the effects of lingual surface (boundary) deformation, an implementation of patterned fiber shortening, and a computational visualization of liquid bolus flow. Representing lingual tissue deformation in terms of its 2D principal Lagrangian strain in the mid-sagittal plane, we demonstrated that the swallow sequence was characterized by initial superior-anterior expansion directed towards the hard palate, followed by sequential, radially directed, contractions of the genioglossus and verticalis to promote lingual rotation (lateral perspective) and propulsive displacement. We specifically assessed local bolus velocity as a function of viscosity (perfect slip conditions) and observed that a low viscosity bolus (5 cP) exhibited maximal displacement, surface spreading and local velocity compared to medium (110 cP, 300 cP) and high (525 cP) viscosity boluses. Analysis of local nodal velocity revealed that all bolus viscosities exhibited a bi-phasic progression, with the low viscosity bolus being the most heterogeneous and fragmented and the high viscosity bolus being the most homogenous and cohesive. Intraoral bolus cohesion was depicted in terms of the distributed velocity gradient, with higher gradients being associated with increased shear rate and bolus fragmentation. Lastly, we made a sensitivity analysis on tongue stiffness and contractility by varying the degree of extracellular matrix (ECM) stiffness through effects on the Mooney-Rivlin derived passive matrix and by varying maximum tetanized isometric stress, and observed that a graded increase of ECM stiffness was associated with reduced bolus spreading, posterior displacement, and surface velocity gradients, whereas a reduction of global contractility resulted in a graded reduction of obtainable accommodation volume, absent bolus spreading, and loss of posterior displacement. We portray a unidirectionally coupled solid-liquid FEM which associates myoarchitecture-based lingual deformation with intra-oral bolus flow, and deduce that local elevation of the velocity gradient correlates with bolus fragmentation, a precondition believed to be associated with aspiration vulnerability during oropharyngeal swallowing.
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Affiliation(s)
- Dana M Leichter
- Center for Biomedical Engineering, Brown University, Providence, RI, 02912, USA; Research Service, Providence VA Medical Center, Providence, RI, 02908, USA
| | - Nicole E Stark
- Department of Mechanical Engineering, Widener University, Chester, PA, 19013, USA
| | - Owen P Leary
- Research Service, Providence VA Medical Center, Providence, RI, 02908, USA; Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Martin B Brodsky
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University, USA
| | - Richard J Gilbert
- Research Service, Providence VA Medical Center, Providence, RI, 02908, USA; Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Mark A Nicosia
- Department of Mechanical Engineering, Widener University, Chester, PA, 19013, USA.
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Ruiz-Huerta L, Palacios-Morales C, Caballero-Ruiz A, Vopalensky M, Díaz O, Hernández-Angulo JA, la Fuente EBD, Ascanio G. X-ray technique for visualization of the bolus flow through an esophageal simulator. J Vis (Tokyo) 2021. [DOI: 10.1007/s12650-021-00743-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Wong LY, Ng ML, Tong ETS. How Accurate Are the Consistency Labels Used in Hong Kong? An Objective Study of the Consistency of Thickened Liquids Using International Dysphagia Diet Standardisation Initiative and Consistometric Measurements. Folia Phoniatr Logop 2021; 74:167-175. [PMID: 34348310 DOI: 10.1159/000518480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 07/13/2021] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES The present study objectively examined the consistency (thickness) of labels that are used in Hong Kong for the population with dysphagia using an International Dysphagia Diet Standardisation Initiative (IDDSI) flow test and Bostwick consistometric measurements. METHODS Liquids were prepared by thickening water to achieve 4 consistency labels (slightly thick, mildly thick, medium thick, and extra thick) according to manufacturer's instructions, employing 2 types of thickening products that are used in Hong Kong, i.e., starch based and gum based. For each consistency label prepared using each thickening product, the IDDSI flow test and consistometric measurements were obtained and compared. RESULTS The results showed that the actual thickness of liquids was highly dependent on the type of thickener (starch based vs. gum based) used. Thickened liquids prepared using the starch-based thickener were generally thinner than the actual value at a lower concentration. CONCLUSION Though prepared strictly following the manufacturer's instructions, the thickened liquids fail to faithfully correlate with the standardized norms established according to the IDDSI framework and the objective consistometric measurement using a Bostwick consistometer. Therefore, caution must be exercised when administering a thickened diet following the manufacturer's instructions for patients with dysphagia.
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Affiliation(s)
- Long Yat Wong
- Speech Science Laboratory, Faculty of Education, University of Hong Kong, Hong Kong, China
| | - Manwa L Ng
- Speech Science Laboratory, Faculty of Education, University of Hong Kong, Hong Kong, China
| | - Eric T S Tong
- Hong Kong Sheng Kung Hui Welfare Council, Hong Kong, China
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Raheem D, Carrascosa C, Ramos F, Saraiva A, Raposo A. Texture-Modified Food for Dysphagic Patients: A Comprehensive Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:5125. [PMID: 34066024 PMCID: PMC8150365 DOI: 10.3390/ijerph18105125] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/30/2021] [Accepted: 05/08/2021] [Indexed: 12/16/2022]
Abstract
Food texture is a major food quality parameter. The physicochemical properties of food changes when processed in households or industries, resulting in modified textures. A better understanding of these properties is important for the sensory and textural characteristics of foods that target consumers of all ages, from children to the elderly, especially when food product development is considered for dysphagia. Texture modifications in foods suitable for dysphagic patients will grow as the numbers of elderly citizens increase. Dysphagia management should ensure that texture-modified (TM) food is nutritious and easy to swallow. This review addresses how texture and rheology can be assessed in the food industry by placing particular emphasis on dysphagia. It also discusses how the structure of TM food depends not only on food ingredients, such as hydrocolloids, emulsifiers, and thickening and gelling agents, but also on the applied processing methods, including microencapsulation, microgels as delivery systems, and 3D printing. In addition, we address how to modify texture for individuals with dysphagia in all age groups, and highlight different strategies to develop appropriate food products for dysphagic patients.
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Affiliation(s)
- Dele Raheem
- Northern Institute for Environmental and Minority Law (NIEM), Arctic Centre, University of Lapland, 96101 Rovaniemi, Finland;
| | - Conrado Carrascosa
- Department of Animal Pathology and Production, Bromatology and Food Technology, Faculty of Veterinary, Universidad de Las Palmas de Gran Canaria, Trasmontaña s/n, 35413 Arucas, Spain;
| | - Fernando Ramos
- Pharmacy Faculty, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal;
- REQUIMTE/LAQV, R. D. Manuel II, Apartado 55142, 4051-401 Porto, Portugal
| | - Ariana Saraiva
- Department of Animal Pathology and Production, Bromatology and Food Technology, Faculty of Veterinary, Universidad de Las Palmas de Gran Canaria, Trasmontaña s/n, 35413 Arucas, Spain;
| | - António Raposo
- CBIOS (Research Center for Biosciences and Health Technologies), Universidade Lusófona de Humanidades e Tecnologias, Campo Grande 376, 1749-024 Lisboa, Portugal
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Qazi WM, Ekberg O, Wiklund J, Kotze R, Stading M. Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing. Dysphagia 2019; 34:821-833. [PMID: 30840137 PMCID: PMC6825639 DOI: 10.1007/s00455-019-09995-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 02/26/2019] [Indexed: 11/25/2022]
Abstract
The characteristics of the flows of boluses with different consistencies, i.e. different rheological properties, through the pharynx have not been fully elucidated. The results obtained using a novel in vitro device, the Gothenburg Throat, which allows simultaneous bolus flow visualisation and manometry assessments in the pharynx geometry, are presented, to explain the dependence of bolus flow on bolus consistency. Four different bolus consistencies of a commercial food thickener, 0.5, 1, 1.5 and 2 Pa s (at a shear rate of 50 s-1)-corresponding to a range from low honey-thick to pudding-thick consistencies on the National Dysphagia Diet (NDD) scale-were examined in the in vitro pharynx. The bolus velocities recorded in the simulator pharynx were in the range of 0.046-0.48 m/s, which is within the range reported in clinical studies. The corresponding wall shear rates associated with these velocities ranged from 13 s-1 (pudding consistency) to 209 s-1 (honey-thick consistency). The results of the in vitro manometry tests using different consistencies and bolus volumes were rather similar to those obtained in clinical studies. The in vitro device used in this study appears to be a valuable tool for pre-clinical analyses of thickened fluids. Furthermore, the results show that it is desirable to consider a broad range of shear rates when assessing the suitability of a certain consistency for swallowing.
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Affiliation(s)
- Waqas M Qazi
- Agrifood and Bioscience, Product Design and Perception, RISE, Research Institutes of Sweden AB, Göteborg, Sweden.
- Department of Industrial and Material Sciences, Chalmers University of Technology, Göteborg, Sweden.
| | - Olle Ekberg
- Diagnostic Centre of Imaging and Functional Medicine, Skåne University Hospital, Lund, Sweden
| | - Johan Wiklund
- Incipientus Ultrasound Flow Technologies AB, Frans Perssons Väg 6, 412 76, Göteborg, Sweden
| | - Reinhardt Kotze
- Incipientus Ultrasound Flow Technologies AB, Frans Perssons Väg 6, 412 76, Göteborg, Sweden
| | - Mats Stading
- Agrifood and Bioscience, Product Design and Perception, RISE, Research Institutes of Sweden AB, Göteborg, Sweden
- Department of Industrial and Material Sciences, Chalmers University of Technology, Göteborg, Sweden
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Hanson B, Jamshidi R, Redfearn A, Begley R, Steele CM. Experimental and Computational Investigation of the IDDSI Flow Test of Liquids Used in Dysphagia Management. Ann Biomed Eng 2019; 47:2296-2307. [PMID: 31218485 PMCID: PMC6838027 DOI: 10.1007/s10439-019-02308-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/11/2019] [Indexed: 11/26/2022]
Abstract
The International Dysphagia Diet Standardisation Initiative (IDDSI) flow test, using a standard 10-mL syringe, is being adopted in many countries for clinical measurement of the consistency of drinks. The working hypothesis is that thickening drinks to retard flow can be advantageous for individuals who struggle to cope with thin drinks. This study assesses how the IDDSI test relates to rheology and clinical knowledge of physiological flows during swallowing. With no pre-existing analytical solution for internal flow through the syringe, a computational model was designed, incorporating rheometry data from a variety of Newtonian and non-Newtonian liquids. The computational model was validated experimentally across the range of liquids but the technique showed limitations in simulating dripping and cohesiveness. Gum-based liquids which were strongly shear-thinning (0.12 < n < 0.25) showed plug-flow characteristics with 90% of the shear occurring in only 22% of the radial dimension. Shear rates were maximal at the nozzle outlet (> 60 times higher than the barrel) and reached 7400/s for the thinnest gum-based liquid. Shear rheology data alone was unable to describe the flow of these drinks. The flow conditions in the test varied according to the type and consistency of liquid, relating to the desired clinical effect.
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Affiliation(s)
- Ben Hanson
- UCL Mechanical Engineering, Torrington Place, London, WC1E 7JE, UK.
| | - Rashid Jamshidi
- UCL Chemical Engineering, Torrington Place, London, WC1E 7JE, UK
| | - Andrew Redfearn
- UCL Mechanical Engineering, Torrington Place, London, WC1E 7JE, UK
| | - Ryan Begley
- UCL Mechanical Engineering, Torrington Place, London, WC1E 7JE, UK
| | - Catriona M Steele
- Toronto Rehabilitation Institute - University Health Network, 550 University Avenue, #12-101, Toronto, ON, M5G 2A2, Canada
- Rehabilitation Sciences Institute, Faculty of Medicine, University of Toronto, 500 University Avenue, Suite 160, Toronto, ON, Canada
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